Ester-terminated polyamides of polymerized fatty acids useful in formulating transparent gels in low polarity liquids

ABSTRACT

A low molecular weight, ester-terminated polyamide may be blended with a liquid hydrocarbon to form a transparent composition having gel consistency. The ester-terminated polyamide is prepared by reacting &#34;x&#34; equivalents of dicarboxylic acid wherein at least 50% of those equivalents are from polymerized fatty acid, &#34;y&#34; equivalents of diamine such as ethylene diamine, and &#34;z&#34; equivalents of monoalcohol having at least 4 carbon atoms. The stoichiometry of the reaction mixture is such that 0.9&lt;/={x/(y+z)}&lt;/=1.1 and 0.1&lt;/={z/(y+z)}&lt;/=0.7. The reactants are heated until they reach reaction equilibrium. The gel contains about 5-50% ester-terminated polyamide with the remainder preferably being pure hydrocarbon. The gels are useful in formulating personal care products and other articles wherein some degree of gel-like or self-supporting consistency is desired.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.08/734,523, filed Oct. 18, 1996, now U.S. Pat. No. 5,783,657, issuedJul. 21, 1998.

TECHNICAL FIELD OF THE INVENTION

The invention relates to gelling agents and in particular to gellantsfor low polarity liquids such as hydrocarbons.

BACKGROUND OF THE INVENTION

Personal care products generally contain one or more active ingredientswithin a carrier formulation. While the active ingredient(s) determinethe ultimate performance properties of the product the carrierformulation is equally critical to the commercial success of theproduct. The rheology of the carrier (also referred to as the "base")largely determines the flow properties of the product, and the flowproperties largely determine the manner in which the consumer will applyor use the product.

For example aluminum chlorohydrate and aluminum-zirconiumtetrachlorohydrex-Gly are metal salts that are commonly used as activeingredients in deodorant and antiperspirant products. Consumers haveshown a preference for applying deodorant from a stick form. Thus, thecarrier in a stick-form deodorant must be a relatively hard substanceand waxy fatty alcohol such as stearyl alcohol has been used as thecarrier in these products. As another example, the active ingredient ina lipstick is the colorant. A lipstick should not be as hard as a stickdeodorant, but of course must maintain its shape when undisturbed atroom temperature. A blend of wax and oil is known to provide aconsistency that is well-suited as a carrier for a lipstick. As a finalexample, shampoo desirably has a viscosity greater than water, and whenthe active ingredient(s) in a shampoo does not have a sufficiently highviscosity, a somewhat viscous carrier material is desirably included inthe shampoo formulation.

From the above examples, it is seen that formulators of personal careproducts depend upon the availability of materials having variousrheological properties, in order to formulate a successful personal careproduct. Materials which have a gel-like character, in that theymaintain their shape when undisturbed but flow upon being rubbed, areoften desired for personal care products.

Transparent (i.e., clear) carriers are needed by formulators who developa personal care product wherein colorant is an active ingredient,because a transparent carrier (as opposed to an opaque carrier) willminimally, if at all, interfere with the appearance of the colorant.However, in recent years consumers have demonstrated an increasingpreference for transparent personal care products such as deodorants andshampoos. There is thus an increasing demand for transparent materialswhich can provide the rheological properties needed for various personalcare products, and particularly which can impart gel-like character to aformulation.

Polyamide resin prepared from polymerized fatty acid and diamine isreported to function as a gellant in formulations developed for personalcare products. For example. U.S. Pat. No. 3,148,125 is directed to aclear lipstick composition formed from polyamide resin compounded with alower aliphatic alcohol and a so-called "polyamide solvent." Likewise,U.S. Pat. No. 5,500,209 is directed to forming a gel or stick deodorant,where the composition contains polyamide gelling agent and a solventsystem including monohydric or polyhydric alcohols. Thus, the prior artrecognizes to blend certain polyamides with alcohols, to thereby form agel.

Certain modified polyamide resins, e.g., polyamides which are onlypartly amidated but contain esterified carboxyl groups, have beenreported to impart high gel strength and pronounced thixotropicproperties to coating compositions that contain alkyd resins or dryingoils. See U.S. Pat. No. 3,141,767 to Goetze et al. However, the modifiedpolyamide resins of Goetze et al. are not disclosed as being usefulgellants in personal care products, nor useful gellants when purehydrocarbon is used as the vehicle.

Pure hydrocarbon is desirably included in a personal care formulationbecause it is transparent and relatively inexpensive. Pure hydrocarbonsare also available in a wide variety of viscosities and grades. However,pure hydrocarbon often does not have the rheological properties that aredesired in a carrier, e.g., it does not naturally exhibit gel-likecharacter. When hydrocarbon is present in a personal care formulationalcohol is also typically present when a gel-like consistency is desiredfor the product. There is a need in the art for materials which can becombined with pure hydrocarbon to afford a transparent material whichhas gel-like character. The present invention provides this and relatedadvantages as described herein.

SUMMARY OF THE INVENTION

The present invention is directed to a resin composition comprisingester-terminated polyamide (ETPA) of formula (1): ##STR1## wherein ndesignates a number of repeating units such that ester groups constitutefrom 10% to 50% of the total of the ester and amide groups; R¹ at eachoccurrence is independently selected from an alkyl or alkenyl groupcontaining at least 4 carbon atoms; R² at each occurrence isindependently selected from a C₄₋₄₂ hydrocarbon group with the provisothat at least 50% of the R² groups have 30-42 carbon atoms; R³ at eachoccurrence is independently selected from an organic group containing atleast two carbon atoms in addition to hydrogen atoms, and optionallycontaining one or more oxygen and nitrogen atoms: and R^(3a) at eachoccurrence is independently selected from hydrogen C₁₋₁₀ alkyl and adirect bond to R³ or another R^(3a) such that the N atom to which R³ andR^(3a) are both bonded is part of a heterocyclic structure defined inpart by R^(3a) --N--R³, such that at least 50% of the R^(3a) groups arehydrogen. Preferably, the resin composition further comprises diesterhaving formula (1) wherein n=0. such that the ratio of ester groups tothe sum of ester and amide groups in the total of the ester-terminatedpolyamide and diester is from 0.1 to 0.7. Preferably, the resincomposition is at reaction equilibrium.

Another aspect of the invention is a method for preparing a resincomposition comprising ester-terminated polyamide. The method comprisesreacting x equivalents of carboxylic acid from diacid or a reactiveequivalent thereof, y equivalents of amine from diamine and zequivalents of hydroxyl from monoalcohol or a reactive equivalentthereof. At least about 50% of the carboxylic acid equivalents are frompolymerized fatty acid, and monoalcohol is substantially the onlymonofinctional reactant used to form the resin. The monoalcohol has atleast four carbon atoms, 0.9≦{x/(y+z)}≦1.1, and 0.1≦{z/(y+z)}≦0.7. Theinvention also includes the resin composition prepared by the inventivemethod.

A further aspect of the invention is a composition comprising a lowpolarity liquid and at least one resin composition which is describedabove, i.e., a resin composition comprising ester-terminated polyamideof formula (1): ##STR2## wherein n, R¹, R² and R³ are set forth above,or the resin composition prepared by the method of reacting xequivalents of carboxylic acid from diacid or a reactive equivalentthereof, y equivalents of amine from diamine and z equivalents ofhydroxyl from monoalcohol or a reactive equivalent thereof as describedabove.

Another aspect of the invention is a method for preparing a transparentor translucent gel. The method comprises combining a low polarity liquidwith a resin composition, where the resin composition contains ETPA asdescribed above, or has been prepared by the methods described above.

A further aspect of the invention is a candle comprising a wick and aresin composition where the resin composition contains ETPA as describedabove, or has been prepared by the methods described above.

Another aspect of the invention is a cosmetic which comprises the resincomposition containing ETPA as described above or which has beenprepared by the methods described above.

The invention also includes articles of manufacture comprisingester-terminated polyamide as described above. Such articles includeantiperspirants and cosmetics, as well as other personal care products(e.g., deodorant, eye make-up, lipstick, foundation make-up, baby oil,make-up removers bath oil, skin moisturizers, sun care products, lipbalm, waterless hand cleaner, medicated ointments, ethnic hair careproducts perfume, cologne, costume make-up and suppositories), candlesand other household products (e.g., automobile wax, automobile polish,firniture polish, metal cleaners, metal polish, household cleaners,paint strippers and insecticide carriers) and industrial products (e.g.,fuels (e.g., sterno, lighters), toilet bowl rings, lubricants, greases,wire rope lubricant, joint and cable fillers, soldering flux, buffingcompounds, crayons and markers, modeling clay, rust preventatives,printing inks, protective/removable coatings and jet inks.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is graphical representation of the effect of temperature onrheology for a gelled hydrocarbon of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to ester-terminated polyamides (ETPA)and a method of preparing a resinous composition (hereinafter, simply "aresin") comprising, in whole or part, ester-terminated polyamide. Aresin comprising ETPA (an "ETPA resin") is useful as a gelling agent forhydrocarbons and other liquids, where the resultant gels are usefulcomponents in, for example, candles, cosmetic formulations and otherproducts that can benefit from gel-like character.

As used herein, ETPA refers to molecules of the formula (1), wherein n,R¹, R² and R³ are later defined herein. ##STR3##

The inventive resin composition typically contains a mixture of ETPAmolecules that may be characterized by the number of amide pairs presentin the molecule, i.e., a portion of the resin may consist of ETPAmolecules having a single amide pair, while another portion of the resinmay consist of ETPA molecules having two amide pairs, etc. The amidepair distribution in the resin, by which is meant the proportion of theresin consisting of ETPA having zero, one, two or three, etc. amidepairs, depends in large part on the stoichiometry of the startingmaterials. The relationship between reactant stoichiometry and resincharacter will be discussed more fully below.

Thus, the invention is directed to an ester-terminated polyamide of theformula (1): ##STR4## wherein n designates a number of repeating unitssuch that ester groups constitute from 10% to 50% of the total of theester and amide groups: R¹ at each occurrence is independently selectedfrom an alkyl or alkenyl group containing at least 4 carbon atoms; R² ateach occurrence is independently selected from a C₄₋₄₂ hydrocarbon groupwith the proviso that at least 50% of the R² groups have 30-42 carbonatoms; R³ at each occurrence is independently selected from an organicgroup containing at least two carbon atoms in addition to hydrogenatoms, and optionally containing one or more oxygen and nitrogen atoms;and R ^(3a) at each occurrence is independently selected from hydrogen,C₁₋₁₀ alkyl and a direct bond to R³ or another R^(3a) such that the Natom to which R³ and R^(3a) are both bonded is part of a heterocyclicstructure defined in part by R^(3a) --N--R³, such that at least 50% ofthe R^(3a) groups are hydrogen. For convenience, R¹, R², R³ etc. will bereferred to herein as "groups", however they could equally well bereferred to as radicals (R¹) and diradicals (R² and R³).

As may be seen from formula (1), the ester-terminated polyamides of theinvention have ester groups,. i.e., --C(═O)O-- groups (which may equallywell be written as --OC(═O)-- groups) at both ends of a series of amidegroups, i.e., --N(R^(3a))C(═O)-- groups (which may equally well bewritten as --C(═O)N(R^(3a))-- groups). The letter "n" designates thenumber of repeating units present in a molecule of ETPA, and is aninteger greater than 0. According to the invention, n may be 1, in whichcase the ETPA contains equal amounts of ester and amide groups, i.e.,the ester groups constitute 50% of the total of the ester and amidegroups in the ETPA molecule. Preferably, the ETPA molecules are ofrelatively low molecular weight, so that n is preferably 1 to about 10,and more preferably is 1 to about 5. Because the ETPA molecules havesuch a low molecular weight, they could equally well be referred to asester-terminated oligoamides. In any event, viewed another way, theester groups constitute about 10% to about 50%, preferably about 15% toabout 40%, and more preferably about 20% to about 35% of the total ofthe ester and amide groups. The invention is also directed to a mixtureof ETPA molecules having various n values.

The R¹ group in formula (1) is an alkyl or alkenyl group which containsat least 4 carbon atoms. Alkyl groups are preferred, however alkenylgroups having 1-3, and preferably 1 site of unsaturation are alsosuitable. When ETPA molecules are made wherein R¹ has 4 or less carbonatoms, the ETPA molecule is a very poor gellant for pure hydrocarbon,particularly pure aliphatic hydrocarbon. However, it has beensurprisingly found that when the number of carbon atoms in the R¹ groupis increased above 4, and preferably has at least about 10 carbon atoms,more preferably at least about 12 carbon atoms, then the ETPA moleculeand blends thereof are an excellent gellant for aliphatic hydrocarbon.The upper range for the number of carbon atoms in the R¹ group is notparticularly critical however preferably the R¹ group has less than orequal to about 24 carbon atoms and more preferably has less than orequal to 22 carbon atoms. R¹ groups having about 16-22 carbon atoms arehighly preferred. The identity of R¹ at any occurrence is independent ofthe identity of R¹ at any other occurrence.

The R² group in formula (1) is a hydrocarbon containing 4 to 42 carbonatoms. A preferred R² group contains 30-42 carbon atoms (i.e., is aC₃₀₋₄₂ group), and in fact at least 50% of the R² groups in an ETPAmolecule or mixture of ETPA molecules according to the invention have30-42 carbon atoms. Such R² groups are readily introduced into an ETPAmolecule when the molecule is prepared from polymerized fatty acid, alsoknown as dimer acid. Polymerized fatty acid is typically a mixture ofstructures, where individual dimer acids may be saturated, unsaturatedcyclic, acyclic, etc. Thus, a detailed characterization of the structureof the R² groups is not readily available. However, good discussions offatty acid polymerization may be found in, e.g, U.S. Pat. No. 3,157,681and Naval Stores--Production, Chemistry and Utilization, D. F. Zinkeland J. Russel (eds.), Pulp. Chem. Assoc. Inc., 1989, Chapter 23.

Typical unsaturated fatty acids used to form polymerized fatty acidinclude oleic acid, linoleic acid, linolenic acid, etc. Tall oil fattyacid, which is a mixture containing long-chain unsaturated fatty acidsobtained as a byproduct of the wood pulping process, is preferred forpreparing polymerized fatty acid useful in the invention. While tall oilfatty acid is a preferred source of long-chain fatty acid, thepolymerized fatty acid may alternatively be prepared by polymerizationof unsaturated fatty acids from other sources, e.g., soybeans or canola.The R² group containing 30-42 carbon atoms may thus be described ashaving the structure of dimer or trimer acid, after removal of thecarboxylic acid groups (as seen below, the carboxylic acid groups ofdimer acid can react to form the amide and/or ester groups of the ETPAmolecules).

While the ETPA molecules of the invention contain at least 50% C₃₀₋₄₂groups as the R² group, preferably the total of the R² groups consist ofat least 75% C₃₀₋₄₂ groups, and more preferably consist of at least 90%C₃₀₋₄₂ groups. An ETPA molecule, and mixture of ETPA molecules. whereinR² is entirely C₃₀₋₄₂ are preferred embodiments of the invention.

However, ETPA molecules may also contain R² groups having less than 30carbon atoms. For example, an ETPA molecule of the invention may containone or more R² groups having about 4 to 19, preferably about 4 to 12,and more preferably about 4 to 8 carbon atoms. The carbon atoms may bearranged in a linear, branched or cyclic fashion, and unsaturation maybe present between any two carbon atoms. Thus. R² may be aliphatic oraromatic. When present, these lower carbon-number R² groups arepreferably formed entirely of carbon and hydrogen, i.e., are hydrocarbongroups. Such lower carbon-number R² groups preferably constitute lessthan 50% of the R₂ groups; however, when present, constitute about 1% toabout 50%. and preferably about 5% to about 35% of the total of the R²groups. The identity of R² at each occurrence is independent of theidentity of R² at any other occurrence.

The --N(R^(3a))--R³ --N(R^(3a))-- group in formula (1) links twocarbonyl (C═O) groups. In a preferred embodiment of the invention, allof the R^(3a) groups in an ETPA molecule are hydrogen, so that R³ alonejoins the two nitrogen atoms shown in the formula --N(R^(3a))--R³--N(R^(3a))--. In this case, the R³ group contains at least two carbonatoms, and optionally oxygen and/or nitrogen atoms, in addition tohydrogen atoms necessary to complete otherwise unfilled vacancies of thecarbon, oxygen and nitrogen atoms. In a preferred embodiment, R³ is ahydrocarbon group, having 2 to about 36 carbon atoms, preferably having2 to about 12 carbon atoms, and more preferably having 2 to about 8carbon atoms. These carbon atoms may be arranged in a linear, branchedor cyclic fashion, and unsaturation may be present between any two ofthe carbon atoms. Thus, R³ may contain aliphatic or aromatic structures.The identities of R³ and R^(3a) at each occurrence are independent oftheir indentities at any other occurrence.

The R³ groups may contain oxygen and/or nitrogen in addition to carbonand hydrogen atoms. A typical oxygen atom-containing R³ group is apolyalkylene oxide, i.e., a group having alternating alkylene groups andoxygen atoms. Indeed, the oxygenation in a R³ group is preferablypresent as an ether group. Representative polyalkylene oxides include,without limitation, polyethylene oxide, polypropylene oxide andcopolymers (either random or block) of ethylene oxide and propyleneoxide. Such oxygenated R³ groups are readily introduced into an ETPAmolecule of the invention through use of JeffamineTm diamines (Texaco,Inc., Houston, Tex.). These materials are available in a wide range ofmolecular weights. While some of the R³ groups may contain oxygen (i.e.,at least about 1%), preferably a minor number (i.e., less than 50%) ofthe R³ groups contain oxygen, and more preferably less than about 20% ofthe R³ groups contain oxygen. The presence of oxygen-containing R³groups tend to lower the softening point of the ETPA.

When present the nitrogen atoms in an R³ group are preferably present assecondary or tertiary amines. A typical nitrogen atom-containing R³group having secondary amine groups is a polyalkylene amine, i.e., agroup containing alternating alkylene groups and amine groups, andsometimes referred to as a polyalkylene polyamine. The alkylene group ispreferably a lower alkylene group. e.g., methylene. ethylene, (i.e.,--CH₂ CH₂ --), propylene etc. A typical polyalkylene amine may berepresented by the formula --NH--(CH₂ CH₂ NH)_(m) CH₂ CH₂ --NH-- whereinm is an integer from 1 to about 5.

However, the nitrogen atoms in the nitrogen-containing R³ group mayalternatively (or additionally) be present as tertiary nitrogen atoms,e.g., they may be present in a heterocycle of the formula: ##STR5##wherein R_(c) is a C₁₋₃ alkyl group.

In the above-described nitrogen atom-containing R³ groups, R^(3a) washydrogen. However, R^(3a) need not be limited to hydrogen. In fact,R^(3a) may be a C₁₋₁₀ alkyl group, preferably a C₁₋₅ alkyl group, andmore preferably a C₁₋₃ alkyl group. In addition, R³ and R^(3a), or twoR^(3a) groups, may together form a heterocyclic structure, e.g., apiperazine structure such as ##STR6##

In this case, the two R^(3a) groups may be seen as joining together toform an ethylene bridge between the two nitrogen atoms, while R³ is alsoan ethylene bridge.

The invention also provides for a composition ("a resin") comprising theETPA molecules as described above. Such a resin includes the ETPAmolecules of formula (1) in addition to, for example, by-products thatare formed during the ETPA-forming reaction. While the ETPA molecules offormula (1) may be purified from such by-products using, e.g.,chromatography or distillation, the by-products are typically eitherminimal in amount or impart desirable properties to the resin, and thusneed not be separated from the ETPA molecules of formula (1).

As described below, alcohols, amines and carboxylic acids are preferredstarting materials to form the ETPA molecules and resins of theinvention. These starting materials are preferably reacted together witha stoichiometry, and under reaction conditions, such that the acidnumber of the resulting resin is less than 25, preferably less than 15,and more preferably less than 10, while the amine number is preferablyless than 10, more preferably less than 5, and still more preferablyless than 1. The softening point of the resin is preferably greater thanroom temperature, more preferably is about 50° C. to about 150° C., andstill more preferably is about 80° C. to about 130° C.

When the reactants and stoichiometry of the ETPA-forming reactiondescribed below are properly chosen, some material of formula (1)wherein n=0, i.e., diester, can be formed. In a preferred embodiment ofthe invention, material of formula (1) wherein n=0 is present in theETPA resin. A preferred resin of the invention contains from 50% to 70%ester groups, based on the total of the amide and ester groups inmolecules of formula (1) (wherein n may be 0) present in the resin. Sucha resin could also be produced by preparing ETPA as described above(having little or no n=0 material), and then preparing diester offormula (1) (n=0 exclusively, having no amide groups) in a separatereaction, and mixing the two materials together

According to the present invention, monoalcohol, diacid includingpolymerized fatty acid, and diamine may be reacted to yield the ETPAresin. The resin is preferably characterized in that further reactiontime does not provide for any significant change in the properties ofthe resin, i.e., the ETPA resin of the invention is substantially atreaction equilibrium. Each of the necessary reactants (monoalcohol,diacid and diarnine) will now be described in turn, followed by adiscussion of optional reactants and exemplary reaction conditions forpreparing ETPA resin of the invention.

The monoalcohol is represented by the formula R¹ --OH, wherein R¹ is ahydrocarbon group having at least four carbon atoms. Thus, themonoalcohol can also be described as a monohydric alcohol. R¹ ispreferably a C₁₀₋₃₆ hydrocarbon, more preferably a C₁₂₋₂₄ hydrocarbon,still more preferably is a C₁₆₋₂₂ hydrocarbon, and yet still morepreferably is a C₁₈ hydrocarbon. As used herein, the term C₁₀₋₃₆ refersto a hydrocarbon group having at least 10, but not more than 36 carbonatoms, and similar terms have an analogous meaning. The carbon atoms ofthe hydrocarbon group may be arranged in a linear, branched or cyclicfashion and the group may be saturated or unsaturated. However, R¹ ispreferably linear, with the hydroxyl group located on a terminal carbonatom, i. e., the monoalcohol is a primary monoalcohol. Thus,1-dodecanol, 1-tetradecanol, 1-hexadecanol (cetyl alcohol),1-octadecanol (stearyl alcohol), 1-eicosanol (arachidyl alcohol) and1-docosanol (behenyl alcohol) are preferred monoalcohols for preparingresins of the invention, where names in parentheses are common ortrivial names by which these monoalcohols are known. While themonoalcohol has been exemplified with saturated alkyl groups, themonoalcohol may alternatively contain an alkenyl group, i.e., an alkylgroup having unsaturation between at least any two adjacent carbonatoms. One or a mixture of these alcohols may be used to prepare a resinof the invention.

Another monoalcohol reactant suited for the invention is a so-calledGuerbet alcohol. Guerbet alcohols have the general formulaH--C(Ra)(Rb)--CH₂ --OH wherein Ra and Rb may be the same or differentand preferably represent a C₆₋₁₂ hydrocarbon group. Further discussionof Guerbet alcohols may be found in, e.g., "Dictionary For AuxiliariesFor Pharmacy, Cosmetics And Related Fields," H. P. Fiedler, 3rd Ed.,1989, Editio Cantor Aulendorf. 2-Hexadecyloctadecanol, which has 24carbon atoms, is a preferred Guerbet alcohol for use in the presentinvention.

Because R¹ is a hydrocarbon, the monoalcohol is a monofunctionalreactant under the reaction conditions emploved to prepare the resin ofthe invention (as discussed later). Furthermore, under preferredreaction conditions, R¹ --OH is the only monoftmctional reactant used toform the inventive resin. Thus, a reactant mixture useful in preparingETPA resin preferably does not contain monocarboxylic acid (i.e., anorganic molecule containing a single carboxylic acid group) and/ormonoamine (i.e., an organic molecule containing a single amine group).

The diacid is represented by the formula HOOC--R² --COOH, and maytherefore be referred to as a dicarboxylic acid, a dibasic acid or adibasic carboxylic acid. R² is a hydrocarbon group where the carbonatoms thereof may be arranged in a linear, branched or cyclic fashion,and the group be saturated or unsaturated. In one embodiment of theinvention, the diacid is exclusively polymerized fatty acid.

Polymerized fatty acid as used to form the resin of the invention is awell known and venerable material of commerce, and thus need not bedescribed in great detail. Polymerized fatty acid is typically formed byheating long-chain unsaturated fatty acids, e.g, C₁₈ monocarboxylicacids, to about 200-250° C. in the presence of a clay catalyst in orderthat the fatty acids polymerize. The product typically comprises dimeracid, i.e., C₃₆ dicarboxylic acid formed by dimerization of the fattyacid, and trimer acid, i.e., C₅₄ tricarboxylic acid formed bytrimerization of the fatty acid. Polymerized fatty acid is typically amixture of structures, where individual dimer acids may be saturated,unsaturated, cyclic, acyclic, etc. A more detailed discussion of fattyacid polymerization may be found in. e.g., U.S. Pat. No. 3,157,681 andNaval Stores-Production, Chemistry and Utilization, D. F. Zinkel and J.Russell (eds.), Pulp. Chem. Assoc. Inc., 1989, Chapter 23.

Because fatty acid polymerization typically forms much more dimer acidthan trimer acid, those skilled in the art may often refer topolymerized fatty acid as dimer acid even though some trimer acid, andeven higher polymerization products, may be present with the dimer acid.It is preferred that the polymerized fatty acid contain less than about10 weight percent of trimer acid, based on the total weight of thepolymerized fatty acid, and that the dimer acid constitute at leastabout 90 weight percent of the polymerized fatty acid. More preferably,the dimer acid constitutes essentially all of the polymerized fattyacid.

Typical unsaturated fatty acids used to form polymerized fatty acidinclude oleic acid, linoleic acid, linolenic acid, etc. Tall oil fattyacid, which is a mixture containing long-chain unsaturated fatty acidsobtained as a byproduct of the wood pulping process, is preferred forpreparing polymerized fatty acid useful in the invention. While tall oilfatty acid is a preferred source of long-chain fatty acid, thepolymerized fatty acid may alternatively be prepared by polymerizationof unsaturated fatty acids from other sources, e.g., soybeans or canola.The polymerized fatty acid useful in the invention is a liquid, with anacid number on the order of about 180 to about 200.

The polymerized fatty acid of the invention may be hydrogenated prior tobeing used in the resin-forming reaction of the invention. Hydrogenationtends to provide for a slightly higher melting point for the inventiveresin, as well as provide the resin with greater oxidative and colorstability. Hydrogenated polymerized fatty acid tends to provide for alighter colored resin, and is a preferred polymerized fatty acid for usein the practice of the present invention.

Polymerized fatty acid, dimer acid, and hydrogenated versions thereofmay be obtained from a number of commercial suppliers. For example,Union Camp Corporation (Wayne, N.J.) sells polymerized fatty acid undertheir UNIDYME® trademark.

In another embodiment of the invention, the diacid used to prepare theETPA resin is a mixture of polymerized fatty acid and "co-diacid," wherethe term co-diacid simply refers to any diacid of formula HOOC--R²--COOH (where R² is defined above) excluding polymerized fatty acid. Anexemplary co-diacid is a so-called "linear" diacid of the formulaHOOC--R² --COOH wherein R² is a linear C₄₋₁₂ hydrocarbon group, and morepreferably is a linear C₆₋₈ hydrocarbon group. Linear diacids suitablefor the present invention include 1,6-hexanedioic acid (adipic acid),1,7-heptanedioic acid (pimelic acid), 1,8-octanedioic acid (subericacid), 1,9-nonanedioic acid (azelaic acid), 1,10-decanedioic acid(sebacic acid), 1,11-undecanedoic acid, 1,12-dodecanedioic acid(1,10-decanedicarboxylic acid), 1,13-tridecanedioic acid (brassylicacid) and 1,14-tetradecanedioic acid (1,12-dodecanedicarboxylic acid).

Another exemplary co-diacid for use in the present invention is thereaction product of acrylic or methacrylic acid (or the ester thereof,with a subsequent hydrolysis step to form an acid) and an unsaturatedfatty acid. For example, a C₂₁ diacid of this type may be formed byreacting acrylic acid with a C₁₈ unsaturated fatty acid (e.g., oleicacid), where an ene-reaction presumably occurs between the reactants. Anexemplary C₂₁ diacid is commercially available from WestvacoCorporation, Chemical Division, Charleston Heights, S.C., as theirproduct number 1550.

Aromatic diacids may be used as the co-diacid. An "aromatic diacid" asused herein is a molecule having two carboxylic acid groups (--COOH) orreactive equivalents thereof (e.g., acid chloride (--COCl) or ester(--COOR)) and at least one aromatic ring ("Ar"). Phthalic acids e.g.,isophthalic acid and terephthalic acid, are exemplary aromatic diacids.The aromatic diacid may contain aliphatic carbons bonded to the aromaticring(s), as in HOOC--CH₂ --Ar--CH₂ --COOH and the like. The aromaticdiacid may contain two aromatic rings, which may be joined togetherthrough one or more carbon bonds, (e.g., biphenyl with carboxylic acidsubstitution) or which may be fused (e.g., naphthalene with carboxylicacid substitution).

The diamine reactant has two amine groups, both of which are preferablyprimary amines, and is represented by the formula HN(R^(3a))--R³--N(R^(3a))H. R^(3a) is preferably hydrogen, but may also be an alkylgroup or may also join together with R³ or another R^(3a) to form aheterocyclic structure. Diamines wherein R^(3a) is not hydrogen, and/orwherein R³ is not a hydrocarbon, may be referred to herein asco-diamines. When present, co-diamines are preferably used in a minoramount compared to the diamines. R³ may be a hydrocarbon group having atleast two carbon atoms, where the carbon atoms may be arranged in alinear, branched or cyclic fashion, and the group may be saturated orcontain unsaturation. Thus, R³ may be aliphatic or aromatic. PreferredR³ hydrocarbon groups have 2 to 36 carbon atoms, more preferred R³hydrocarbon groups have 2 to 12 carbon atoms. and still more preferredhydrocarbon groups have 2 to 6 carbon atoms.

Exemplary diarnines having hydrocarbon R³ groups, which are commerciallyavailable include, without limitation, ethylenediamine (EDA),1,2-diaminopropane. 1,3-diaminopropane, 1,4-diaminobutane,1,2-diamino-2-methylpropane, 1,3-diaminopentane, 1,5-diaminopentane,2,2-dimethyl-1,3-propanediamine, 1,6-hexanediamine (also known ashexamethylenediamine, HMDA), 2-methyl-1,5-pentanediamine,1,7-diaminoheptane, 1,8-diaminooctane, 2,5-dimethyl-2,5-hexanediamine,1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane,diaminophenanthrene (all isomers, including 9,10),4,4'-methylenebis(cyclohexylamine), 2,7-diaminofluorene, phenylenediamine (1,2; 1,3 and/or 1,4 isomers), adamantane diamine,2,4,6-trimethyl-1,3-phenylenediamine, 1,3-cyclohexanebis(methylamine),1,8-diamino-p-menthane, 2,3,5,6-tetramethyl-1,4-phenylenediamine,diaminonaphthalene (all isomers, including 1,5; 1,8; and 2,3) and4-amino-2,2,6,6-tetramethylpiperidine.

Suitable aromatic diamines (by which is meant molecules having tworeactive, preferably primary amine groups (--NH₂) and at least onearomatic ring ("Ar") include xylene diamine and naphthalene diamine (allisomers).

The R³ group of the diamine may contain oxygen atoms in the form of apolyalkylene oxide group, in which case the diamine may be referred toas a co-diamine. Exemplary polyalkylene oxide-based co-diamines include,without limitation, the JEFFAMINE™ diamines, i.e.,poly(alkyleneoxy)diamines from Texaco, Inc. (Houston, Tex.), also knownas polyether diarnines. Preferred polyalkylene oxide-containingco-diamines are the JEFFAMINE® ED and D series diamines.Ether-containing R³ groups are not preferred, as they tend to lower themelting point of the resin to an undesirable extent. However, smallamounts of a polyalkylene oxide-based diamine with a major amount ofhydrocarbon-based diamine are well-suited for use in the invention. Ingeneral, the diarnine reactant may be a pure diamine as described above,or a mixture of such diamines.

The R³ group of the diamine may contain nitrogen atoms, where thesenitrogen atoms are preferably secondary or tertiary nitrogen atoms. Atypical nitrogen atom-containing R³ group having secondary nitrogenatoms is a polyalkylene amine, i.e., a group containing alternatingalkylene groups and amine groups (i.e., --NH-groups). The alkylene groupis preferably ethylene. i.e., --CH₂ CH₂ --, and the polyalkylene aminemay be represented by the formula NH₂ --(CH₂ CH₂ NH)_(m) CH₂ CH₂ --NH₂wherein m is an integer from 1 to about 5. Diethylenetriamine (DETA) andtriethylenetetraamine (TETA) are representative examples. When thediamine contains two primary amines in addition to secondary amines, theETPA-forming reaction is preferably conducted at relatively lowtemperature, so that the primary amines (in preference to the secondaryamines) react with the diacid component.

However, the nitrogen atoms in the nitrogen-containing R³ group may alsobe present as tertiary nitrogen atoms, e.g., they may be present in aheterocycle of the formula: ##STR7## wherein R_(c) is a C₁₋₃ alkylgroup. Bis(aminoethyl)-N,N'-piperazine andbis(aminopropyl)-N,N'-piperazine may be used to introduce these R³groups into an ETPA molecule, and these are such co-diamines accordingto the invention. In addition, the co-diamine may have one primary aminegroup and one secondary amine group (e.g., N-ethylethylenediamine or1-(2-aminoethyl)piperazine). Generally, it is preferred that aminecompounds having secondary amines not be present in the reaction mixtureto any great extent, because their incorporation into an esterterminated polyamide tends to provide for poorer gelling ability of theester-terminated polyamide.

In general, the diamine reactant may have the formula HN(R^(3a))--R³--NH(R^(3a)) wherein R^(3a) is preferably hydrogen, but may also beC₁₋₁₀ alkyl, preferably C₁₋₅ alkyl, and more preferably C₁₋₃ alkyl. Inaddition, R^(3a) may join together with R³ or ;another R^(3a) group toform a heterocyclic structure. For example, when piperazine is used as aco-diamine, the two R^(3a) groups in the HN(R^(3a))--R³ --NH(R^(3a))structure have joined together to form an ethylene bridge.

Reactive equivalents of diacids and/or diamines may be used in theinvention. For example, diesters may be substituted for some or all ofthe diacid, where "diesters" refer to the esterification product ofdiacid with hydroxyl-containing molecules. However, such diesters arepreferably prepared from relatively volatile hydroxyl-containingmolecules, in order that the hydroxyl-containing molecule may be easilyremoved from the reaction vessel subsequent to monoalcohol and/ordiamine (both as defined herein) reacting with the diester. A loweralkyl diester, e.g., the esterification or diesterification product ofdiacid as defined herein and a C₁₋₄ monohydic alcohol (e.g., methanol,ethanol, propanol and butanol), may be used in place of some or all ofthe diacid in the ETPA-resin forming reaction of the invention. The acidhalide of the diacid may likewise be employed in place of some or all ofthe diacid. however such a material is typically much more expensive anddifficult to handle compared to the diacid, and thus the diacid ispreferred. Likewise, the monoalcohol may be esterified with a volatileacid, e.g., acetic acid, prior to being employed in the ETPAresin-forming reaction of the invention. While such reactive equivalentsmay be employed in the reaction, their presence is not preferred becausesuch equivalents introduce undesired reactive groups into the reactionvessel.

In preparing a resin of the invention the above-described reactants maybe combined in any order. Preferably, the reactants are simply mixedtogether and heated for a time and at a temperature sufficient toachieve essentially complete reaction, to thereby form the inventiveresin. The terms "complete reaction" and "reaction equilibrium" as usedherein have essentially the same meaning, namely that further heating ofthe product resin does not result in any appreciable change in theperformance characteristics of the product resin, where the mostrelevant performance characteristic is the ability of the product resinto form a clear, firm gel upon being combined with a liquid hydrocarbon(as mentioned above and discussed further below).

Thus, the ETPA resin may be formed in a one-step procedure, wherein allof the monoalcohol, diacid (including co-diacid) and diamine (includingco-diamine) are combined and then heated to about 200-250° C. for a fewhours, typically 2-8 hours. As one or more of the reactants may be asolid at room temperature, it may be convenient to combine each of theingredients at a slightly elevated temperature, and then form ahomogeneous mixture prior to heating the reaction mixture to atemperature sufficient to cause reaction between the monoalcohol, diacidand diamine. Alternatively, although less preferably, two of thereactants may be combined and reacted together, and then the thirdreactant is added followed by further heating the desired product isobtained. Reaction progress may be conveniently monitored byperiodically measuring the acid and/or amine number of the productmixture. As one example, the diacid may be reacted with the diamine soas to form polyamide, and then this intermediate polyamide may bereacted with monoalcohol to form ester-terminated polyamide. Or, thediacid may be reacted with the monoalcohol to thereby form diester, andthis diester may be reacted with diamine to thereby formester-terminated polyamide. Because the components of the product resinare preferably in reaction equilibrium (due to transamidation andtransesterification reactions), the order in which the reactants arecombined preferably does not impact on the properties of the ETPA resin.

Any catalyst that may accelerate amide formation between carboxylic acidand arnine groups, and/or ester formation between carboxylic acid andhydroxyl groups, may be present in the reaction mixture described above.Thus, mineral acid such as phosphoric acid, or tin salts such asdibutyltin oxide, may be present during the reaction. In addition, it ispreferred to remove water from the reaction mixture as it is formed uponamide and ester formation. This is preferably accomplished bymaintaining a vacuum on the reacting mixture.

It is important to control the stoichiometry of the reactants in orderto prepare ester-terminated polyamide according to the invention. In thefollowing discussion regarding reactant stoichiometry, the terms"equivalent(s)" and "equivalent percent" will be used, and are intendedto have their standard meanings as employed in the art. However, foradditional clarity, it is noted that equivalents refer to the number ofreactive groups present in a molar quantity of a molecule, such that amole of a dicarboxylic acid (e.g., sebacic acid) has two equivalents ofcarboxylic acid, while a mole of monoalcohol has one equivalent ofhydroxyl. Furthermore, it is emphasized that the diacid has only tworeactive groups (both carboxylic acids), the monoalcohol has only onereactive group (a hydroxyl group) and the diamine has only two reactivegroups (preferably both primary amines), and these are preferably,although not necessarily, the only reactive materials present in thereaction mixture.

According to the invention, is it preferred that the equivalents ofcarboxylic acid are substantially equal to the combined equivalents ofhydroxyl contributed by monoalcohol and amine contributed by diamine. Inother words, if the reaction mixture used to form an ETPA resin has "x"equivalents of carboxylic acid, "y" equivalents of amine and "z"equivalents of hydroxyl, then 0.9≦{x/(y+z)}<1.1, and preferably{x/(y+z)} is substantially 1.0. Under these conditions, substantiallyall of the carboxylic acid groups will react with substantially all ofthe hydroxyl and amine groups, so that the final product contains verylittle unreacted carboxylic acid, hydroxyl or amine groups. In otherwords, each of the acid and amine numbers of a resin of the invention ispreferably less than about 25, is more preferably less than about 15,and is more preferably less than about 10, and is still more preferablyless than about 5.

When co-diacid is employed to prepare an ETPA resin, the co-diacidpreferably contributes no more than about 50% of the equivalents ofcarboxylic acid present in the reaction mixture. Stated another way, theco-diacid contributes from 0-50 equivalent percent of the acidequivalents in the reaction mixture. Preferably, the co-diacidcontributes 0-30 equivalent percent, and more preferably contributes0-10 equivalent percent of the acid equivalents in the reaction mixture.

When co-diamine is employed to prepare an ETPA resin, the co-diaminepresent in the reaction mixture. Stated another way, the co-diaminecontributes from 0-50 equivalent percent of the amine equivalents in thereaction mixture. Preferably, the co-diamine contributes 0-30 equivalentpercent, and more preferably contributes 0-10 equivalent percent of theamine equivalents in the reaction mixture.

In order to prepare the resin of the invention, it is important tocontrol the relative equivalents of hydroxyl and amine used in theresin-forming reaction. Thus, hydroxyl groups contribute about 10-70% ofthe total equivalents of hydroxyl and amine employed to prepare anester-terminated polyamide-containing resin of the invention. Statedanother way, 0.1≦{z/(y+z)}≦0.7, where y and z have been defined above.In a preferred embodiment, 0.2≦{z/(y+z)}≦0.5, while in a furtherpreferred embodiment, 0.25≦{z/(y+z)}≦0.4.

The stoichiometry of the reactants will have a significant impact on thecomposition of the ETPA resin. For example, ETPA resins made withincreasing amounts of monoalcohol will tend to have lower averagemolecular weights. In other words, as more monofunctional reactant isused, the number of amide pairs in an average ETPA molecule of the resinwill tend to decrease. In fact, when 70 equivalent percent monoalcoholis employed, the majority of the ETPA molecules in the resin will haveonly one or two amide pairs. On the other hand, as less monoalcohol isused, the average molecular weight of the ETPA in the resulting resinwill increase. In general, increasing the average molecular weight forthe ETPAs in a resin will tend to increase the melting point and meltviscosity of the resin, which tends to provide a firmer gel when theETPA resin is combined with a low polarity liquid.

As stated above, the ester-terminated polyamides described herein areuseful in forming gels with liquid hydrocarbons (as well as otherliquids) at room temperature, and accordingly preferably have asoftening point greater than room temperature. A precise definition of"gel" is not easy to give, although most if not all researchersrecognize a "gel." Generally, a gel is more viscous than a liquid orpaste, and retains its shape when left undisturbed, i.e., isself-supporting. However, a gel is not as hard or firm as a stick orwax. Gels may be penetrated more easily than a wax-like solid, where"hard" gels are relatively more resistant to penetration than "soft"gels.

Almdale et al. (Polymer Gels and Networks, Vol. 1, No. 5 (1993)) listtwo criteria for defining a system as a gel: (1) a gel consists of twoor more components, one of which is a liquid, present in substantialquantities; and (2) a gel is a soft material which is solid orsolid-like. This latter requirement can be described more accuratelythrough rheological measurement. Typically, gels possess a storagemodulus G'(w) which exhibits a pronounced plateau at higher frequencies(on the order of 1-100 radians/second), and a loss modulus G"(w) whichis considerably smaller than the storage modulus in the plateau region.In a strict sense, the term "gel" applies to systems having a valueG'(w) that is higher than its value of G"(w) at low frequencies. Many ofthe compositions according to the present invention are gels by one orboth of the above definitions. A gel is free-standing or self-supportingin that its yield value is greater than the sheer stress imposed bygravity.

Rheological parameters such as the storage modulus G'(w) can be measuredas a function of angular frequency with a parallel-plate rheometer. Forexample, such parameters can be generated using a Rheometrics DynamicAnalyzer Model 70, using a 0.5 cm stainless steel plate and a 2.3 mmsample gap, over a temperature sweep of 25-85° C. at 1% strain and 6.3radians/sec. A characterization of the rheological behavior of a gelaccording to the present invention was made using the Rheometricsinstrument and conditions set forth above. The gel was preparedaccording to Example 3 set forth herein. As demonstrated by FIG. 1, theelastic modulus (G') is 5-10 fold greater than the loss modulus (G") atroom temperature for this composition, thus demonstrating that a gelstructure is present. As the gel is heated, it retains significantgel-like character at least up to about 50° C. However, as the gel isfurther heated, and the melting point of the ester-terminated polyamideresin is reached. the loss modulus will eventually equal the storagemodulus (i.e., tan δ equals 1), and the composition loses its gel-likecharacter (at a temperature of about 65-70° C., based on extrapolationof the data in FIG. 1).

A commercially desirable aspect of the invention is that the gel may be(although need not be) essentially transparent. Thus, the gels aredesirably combined with colorants, as well as other ingredients, to formlipstick and other cosmetic products. The advantage of a clear gel inthese applications is that the gel imparts little if any undesirablecolor to the lipstick or cosmetic. The gels may be combined withaluminum zirconium salts, as well as other ingredients, to formcolorless underarm deodorant/antiperspirant, which is currently quitepopular. The gels of the invention are also useful in other personalcare products, e.g., cosmetics such as eye make-up, lipstick, foundationmake-up, costume make-up, as well as baby oil, make-up removers, bathoil, skin moisturizers, sun care products, lip balm, waterless handcleaner, medicated ointments, ethnic hair care products, perfume,cologne, and suppositories. In addition, the gels may be used inhousehold products such as automobile wax/polish, candles, furniturepolish, metal cleaners/polishes, household cleaners, paint strippers andinsecticide carriers.

The gels may also be used in industrial products such as fuels (sterno,lighters), toilet bowl rings, lubricants/greases, wire rope lubricant,joint and cable fillers, soldering flux, buffing compounds, crayons andmarkers, modeling clay, rust preventatives, printing inks,protective/removable coatings, and jet inks. For example, hydrocarbongelled with an ETPA resin of the invention may be used as a heat sourcein, e.g., a cooking apparatus used in camping and hiking. Such acomposition will not flow if tilted, and thus may be safer and neaterthan similar products made from flowing materials.

Formulations to prepare such materials are well known in the art. Forexample, U.S. Pat. Nos. 3,615,289 and 3,645,705 describe the formulationof candles. U.S. Pat. Nos. 3,148,125 and 5,538,718 describe theformulation of lipstick and other cosmetic sticks. U.S. Pat. Nos.4,275,054, 4,937,069, 5,069,897, 5,102,656 and 5,500,209 each describethe formulation of deodorant and/or antiperspirant. Each of these U.S.Patents is hereby incorporated fully herein by reference.

The ETPA resin of the invention may be incorporated into commercialproducts such as those listed above by blending the ETPA resin with theother components of the product. Typically, the ETPA resin will bepresent at a concentration of about 1% to about 50% of the composition,based on the total weight of the composition. It is a routine matter tooptimize the amount of ETPA resin to have present in a composition, andindeed the amount will vary depending on the actual product and thedesired consistency of the product. In general, as more ETPA resin isused in a formulation, the product will display a more pronounced gelcharacter.

Accordingly, another aspect of the invention is a gel formed betweeningredients comprising ester-terminated polyamide as described above anda nonaqueous liquid, preferably a low-polarity liquid. A preferred lowpolarity liquid is a hydrocarbon, with preferred hydrocarbons beingsolvents and oils. Solvents and oils may be distinguished in thatdefatting occurs when solvents are rubbed on human skin, leading todrying and irritation. However, defatting does not occur when oils arerubbed on human skin. Oils are more preferred than solvents in mostpersonal-care formulations, and thus are preferred in forming the gelsof the present invention. Preferably, the hydrocarbon has a relativelyhigh number of carbon atoms, e.g., 10 to 30 carbon atoms, and thus isnot a volatile hydrocarbon.

A preferred oil is mineral oil, also sometimes referred to as medicinaloil. Mineral oil is a highly refined, colorless, tasteless, and odorlesspetroleum oil (i.e., derived by processing petroleum/crude oil) usedmedicinally as an internal lubricant and for the manufacture of salvesand ointments. Such mineral oils are highly refined in havingsubstantially all volatile hydrocarbons removed therefrom, and in beinghydrogenated (also called hydrotreated) in order to remove substantiallyall unsaturation, e.g., aromatic groups have been reduced to the fullysaturated analog. A preferred mineral oil to prepare a gel of theinvention is so-called "white" mineral oil, which is water-white (i.e.,colorless and transparent) and is generally recognized as safe forcontact with human skin. Mineral oil may also be characterized in termsof its viscosity, where light mineral oil is relatively less viscousthan heavy mineral oil, and these terms are defined more specifically inthe U.S. Pharmacopoeia, 22^(nd) revision, p. 899 (1990). Any mineral oilmay be used in the invention to form a gel.

Other hydrocarbons that may be used in the invention include relativelylower molecular weight hydrocarbons including linear saturatedhydrocarbons such a tetradecane, hexadecane, octadecane, etc. Cyclichydrocarbons such as decahydronaphthalene (DECALIN), fuel gradehydrocarbons, branched chain hydrocarbons such as PERMETHYL fromPermethyl Corporation and ISOPAR from Exxon Corp., and hydrocarbonmixtures such as product PD-23 from Witco (Greenwich, Conn.) may also beused in preparing gels of the invention. Such hydrocarbons, particularlysaturated hydrocarbon oils, are a preferred liquid for preparing a gelof the invention because such hydrocarbons are often less irritating tothe skin than liquids containing aromatic, ketone and other functionalgroups.

Another class of suitable low polarity liquids are esters, andparticularly esters of fatty acids. Such esters may be monofunctionalesters (i.e., have a single ester moiety) or may be polyfunctional(i.e., have more than one ester group). Suitable esters include, but arenot limited to, the reaction products of C₁₋₂₄ monoalcohols with C₁₋₂₂monocarboxylic acids, where the carbon atoms may be arranged in alinear, branched and/or cyclic fashion, and unsaturation may optionallybe present between carbon atoms. Preferably, the ester has at leastabout 18 carbon atoms. Examples include, but are not limited to, fattyacid esters such as isopropyl isostearate, n-propyl myristate, isopropylmyristate, n-propyl palmitate, isopropyl palmitate, hexacosanylpalmitate, octacosanyl palmitate, triacontanyl palmitate, dotriacontanylpalmitate, tetratriacontanyl palmitate, hexacosanyl stearate,octacosanyl stearate, triacontanyl stearate, dotriacontanyl stearate andtetratriacontanyl stearate; salicylates, e.g., C₁₋₁₀ salicylates such asoctyl salicylate, and benzoate esters including C₁₂₋₁₅ alkyl benzoate,isostearyl benzoate and benzyl benzoate.

Suitable esters are those commonly employed in the cosmetics industryfor the formulation of lipstick and make-up, e.g., the fatty acid estersmentioned above, and are often denoted as "cosmetic esters". Othercosmetic esters include glycerol and propylene glycol esters of fattyacids, including the so-called polyglycerol fatty acid esters andtriglycerides. Exemplary cosmetic esters include, without limitation,propylene glycol monolaurate, polyethylene glycol (400) monolaurate,castor oil, triglyceryl diisostearate and lauryl lactate. Thus, theliquid may have more than one of ester, hydroxyl and etherfunctionality. For example, C₁₀₋₁₅ alkyl lactate may be used in a gel ofthe invention. In addition, esterified polyols such as the polymersand/or copolymers of ethylene oxide, propylene oxide and butylene oxidereacted with C₁₋₂₂ monocarboxylic acids are useful. The carbon atoms ofthe C₁₋₂₂ monocarboxylic acids may be arranged in a linear, branchedand/or cyclic fashion, and unsaturation may be present between thecarbon atoms. Preferred esters are the reaction product of an alcoholand a fatty acid, where the alcohol is selected from C₁₋₁₀ monohydricalcohol, C₂₋₁₀ dihydric alcohol and C₃₋₁₀ trihydric alcohol, and thefatty acid is selected from a C₈₋₂₄ fatty acid.

The gels of the invention preferably do not contain substantial amountsof monoalcohol, i.e., monohydric alcohols having a single hydroxyl andtheir only functional group. Thus, the gels of the invention preferablycontain less than 25 weight percent, more preferably less than 10 weightpercent, and still more preferably less than 5 weight percent ofmonoalcohol. It is a surprising advantage of the present invention thatthe ETPA resin can gel hydrocarbon in the absence of hydroxyl-containingcompounds.

The gels of the invention are preferably self-supporting, in that theyretain their shape at room temperature and in the absence of shear.Also, the inventive gels are preferably clear or translucent. The termsclear, transparent and clarity are intended to have their ordinarydictionary definitions; thus, a clear gel allows ready viewing ofobjects behind it. By contrast, a translucent gel, although allowinglight to pass through, causes the light to be so scattered that it willbe impossible to see clearly objects behind the translucent stick. Asused herein, a gel is transparent or clear if the maximum transmittanceof light of any wavelength in the range 400 to 800 nm through a sample 1cm thick is at least 35%, preferably at least 50% (see, e.g., EuropeanPatent Publication No. 291,334 A4). The gel is translucent if themaximum transmittance of such light through the sample is between 2% andless than 35%. The transmittance can be measured by placing a sample ofthe aforementioned thickness into a light beam of a spectrophotometerwhose working range includes the visible spectrum, such as a Bausch &Lomb Spectronic 88 Spectrophotometer.

The gels of the invention preferably do not display syneresis. Asdefined in the McGraw-Hill Dictionary of Scientific and Technical Terms(3^(rd) Edition), syneresis is the spontaneous separation of a liquidfrom a gel or colloidal suspension due to contraction of the gel.Typically, syneresis is observed as the separation of liquid from a gel,and is sometimes referred to as "bleeding", in that wetness is seenalong the surfaces of a gel that displays syneresis. From a commercialpoint of view, syneresis is typically an undesirable property, and thegels of the present invention desirably, and surprisingly do not exhibitsyneresis.

To prepare a gel of the invention, an ester-terminated polyamide resinis combined with a liquid. The two ingredients are taken to elevatedtemperature, e.g., up to about 80-150° C., until the resin completelydissolves in the liquid. A lower temperature may be used if a solutioncan be prepared at the lower temperature. Upon cooling, the mixtureforms the gel of the invention. Preferably, the liquid is a low-polarityliquid as described above, and more preferably the liquid is ahydrocarbon. The liquid may contain more than one component, e.g.,hydrocarbon as well as ester-containing material. In any event, theester-terminated polyamide is combined with the liquid such that theweight percent of ETPA in the ETPA+solvent mixture is about 5-50%, andpreferably is about 10-45%. Such gels may be transparent, translucent oropaque, depending on the precise identities of the ester-terminatedpolyamide and liquid, as well as the concentration of ETPA in themixture.

The gels of the invention may be formulated into personal care productsaccording to techniques well known in the art. The gel may be combinedwith ingredients conventionally incorporated into personal care productssuch as chelating agents, colorants, emulsifiers, fillers, hardeners,perfumes, strengtheners, water and wax, to name a few. Such additivesare also set forth in, e.g., the following documents, all incorporatedby reference herein in their entirety: U.S. Pat. Nos. 3,255,082 toBarton, 4,049,792 to Elsnau, 4,137,306 to Rubino et al., and 4,279,658to Hooper et al.,

Personal care products may be prepared from the ETPA resin of theinvention by mixing the various components of the product at an elevatedtemperature and then cooling in order to form the gelled (solidified)composition. Desirably, any volatile components are added to the mixtureat a relatively late stage of the mixing, so as to limit volatilizationof the component. Preferably, the liquid and ETPA gelling agent aremixed and heated so as to fully dissolve the ETPA in the liquid (e.g.,at 80° C.-150° C.). An active ingredient (e.g., active antiperspirant)can be added after the ETPA fully dissolves, and mixing then takesplace. Mixing may continue during cooling, with colorant or othercomponent being added during the cooling stage.

The following examples are set forth as a means of illustrating thepresent invention and are not to be construed as a limitation thereon.

In the following Examples, softening point was measured using a ModelFP83HT Dropping Point Cell from Mettler Instruments Corporation, with aheating rate of 1.5° C./min. Viscosity measurements were made using aModel RVTD Digital Viscometer from Brookfield Engineering Laboratories,Inc., and are reported in centipoise (cP). Gel clarity and hardness wereboth judged qualitatively.

In the synthesis Examples that follow, and unless otherwise noted, thechemicals were all of reagent grade, obtained from commercial supplyhouses including Aldrich Chemical Co. (Milwaukee, Wis.) and the like.Unidyme™ 14 polymerized fatty acid is a dimer acid available from UnionCamp Corp., Wayne, N.J. Empol™ 1008 polymerized fatty acid is a dimeracid available from Henkel Corporation, Ambler, Pa. Pripol™ 1008polymerized fatty acid is a dimer acid available from Unichema NorthAmerica, Chicago, Ill. Harchemex™ (Union Camp Co., Wayne N.J.) alcoholis a 60/40 blend of C₁₄ /C₁₆ linear alcohols.

EXAMPLES EXAMPLE 1 ETPA From C₁₄ -C₁₆ Linear Alcohol

This Example shows that a clear, soft gel can be made with an ETPAsynthesized from a blend of linear alcohols having chain lengths of 14and 16 carbons.

The components and amounts thereof as shown in Table 1 were charged to areaction vessel and heated at 200-220° C. under a nitrogen atmospherefor 2 hours. The resulting ETPA had a softening point of 68.5° C. and aviscosity of 44 centipoise at 130° C., as summarized in Table 2.

                  TABLE 1                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.14 /C.sub.16                              ALCOHOL-TERMINATED POLYAMIDE                                                    Reactant         % Equivalents                                                                            Weight %                                      ______________________________________                                        Unidyme ™ 14  100        65.6                                                Hexamethylene diamine 50 6.5                                                  Harchemex 50 27.8                                                           ______________________________________                                    

This ETPA was combined with tetradecane (20 wt % ETPA/80 wt %tetradecane ) and heated until the ETPA dissolved in the tetradecane.Upon cooling to room temperature, the solution formed a soft clear gel,summarized in Table 2.

EXAMPLE 2 ETPA From C₂₂ Linear Alcohol

This example shows that a clear, soft gel can be made with an ETPAsynthesized from a linear alcohol having a chain length of 22 carbons.

The starting materials used to prepare the ETPA are identified in Table3 and the properties of the resulting ETPA are given in Table 2. Theresin and the gel were made in the manner described in Example 1.

                  TABLE 3                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.22                                        ALCOHOL-TERMINATED POLYAMIDE                                                    Reactants        % Equivalents                                                                            Weight %                                      ______________________________________                                        Pripol ™ 1009 100        56.6                                                Hexamethylene diamine 40 4.6                                                  Behenyl alcohol 60 38.8                                                     ______________________________________                                    

EXAMPLE 3 ETPA From C₁₈ Linear Alcohol

This example shows that a clear, soft gel can be made with an ETPAsynthesized from a linear alcohol having a chain length of 18 carbons.

Using the reactants identified in Table 4, an ETPA was synthesized bycharging the diacid and alcohol to a reaction vessel at roomtemperature, heating the mixture under nitrogen to 80° C., adding thediamine, heating to 220° C., holding at 220° C. for 1 hour, and finallyholding under vacuum (8-10 mbar) at 220° C. for 2 hours. As summarizedin Table 2, the ETPA had a softening point of 85.7° C. and a viscosityat 190° C. of 27 cp.

                  TABLE 4                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.18                                        ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        71.9                                                  Ethylene Diamine 65 4.8                                                       Stearyl Alcohol 35 23.3                                                     ______________________________________                                    

A gel was formed from this ETPA according to the procedure described inExample 1. As characterized in Table 2, the gel was clear and hard.

EXAMPLE 4 ETPA From C₂₄ Branched-Chain Alcohol

This example shows that a clear, hard gel can be made with an ETPAsynthesized from a branched alcohol having a chain size of 24 carbons.

An ETPA was synthesized according to the procedure described in Example3, using the reactants as identified in Table 5. The resultant ETPAresin had a softening point of 85.2° C. and a viscosity of 20 cP at 190°C.

                  TABLE 5                                                         ______________________________________                                        REACTANTS TO FORM A BRANCHED C.sub.24                                           ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        64.7*                                                 Ethylene Diamine 60 4.0                                                       Iso Tetracosanol 40 31.3                                                    ______________________________________                                    

A gel was prepared from this ETPA according to the procedure describedin Example 1. As summarized in Table 2, the gel was clear and hard.

EXAMPLE 5 ETPA From C₁₀ Linear Alcohol

This example shows that an opaque gel in tetradecane is formed when anETPA made from a linear alcohol having a chain length of 10 carbons isused.

The ETPA was synthesized in the manner described in Example 3 using thereactants identified in Table 6. As summarized in Table 2, the ETPA hada softening point of 93.2° C. and a viscosity at 190° C. of 29 cp.

                  TABLE 6                                                         ______________________________________                                        REACTANTS TO FORM A LINEAR C.sub.10                                             ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        79.5                                                  Ethylene Diamine 65 5.4                                                       n-Decanol 35 15.1                                                           ______________________________________                                    

This ETPA was combined with tetradecane to form a gel according to theprocedure of Example 1. The gel was opaque and hard, as summarized inTable 2.

EXAMPLE 6 ETPA with moderate C₄ Linear Alcohol termination

This example shows that an opaque gel in tetradecane is formed when anETPA made from a linear alcohol having a chain length of 4 carbons isused.

With one exception, the ETPA was synthesized in the manner described inExample 3, using the reactants set forth in Table 7. In this Examplehowever, excess butanol was added to the formulation before the vacuumstage, to thereby reduce the acid number to 10-15. As summarized inTable 2, the gel had a softening point of 86.3° C. and a viscosity of 35cp at 190° C.

                  TABLE 7                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.4                                         ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        88.5                                                  Ethylene Diamine 65 5.8                                                       n-Butanol 35 7.7                                                            ______________________________________                                    

A gel was made from this ETPA as described in Example 1. The gel wasopaque and soft, and showed syneresis (i.e., "bleeding" of tetradecanefrom the gel), which is undesirable.

EXAMPLE 7 ETPA From with high C₄ Linear Alcohol termination

This example shows that a clear gel in tetradecane is formed when anETPA made from a linear alcohol having a chain length of 4 carbons at arelatively high concentration (50% eq.) is used.

An ETPA was synthesized in the manner described in Example 6, againusing excess butanol before the vacuum stage in order to reduce the acidnumber to 10-15. The reactants used to form this ETPA are set forth inTable 8. The product ETPA has a softening point of 77.2° C. and aviscosity of 15 cP at 190° C.

                  TABLE 8                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.4                                         ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        84.8                                                  Ethylene Diamine 50 4.4                                                       n-Butanol 50 10.8                                                           ______________________________________                                    

A gel was made using this ETPA, according to the procedure described inExample 1. The gel was clear and hard (see Table 2).

EXAMPLE 8 ETPA From with low C₁₈ Linear Alcohol termination

This example shows that there is a lower limit to the alcoholconcentration that can be used in an ETPA, and still obtain atransparent gel therefrom. Below this limit, opaque gels in tetradecaneare formed.

An ETPA was synthesized according to the procedure of Example 3, usingthe reactants identified in Table 9. The ETPA has a softening point of90.4° C. and a viscosity of 47 cp at 190° C.

                  TABLE 9                                                         ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.18                                        ALCOHOL-TERMINATED POLYAMIDE                                                     Reactant      % Equivalents                                                                            Weight %                                        ______________________________________                                        Empol ™ 1008                                                                              100        76.4                                                  Ethylene Diamine 75 5.9                                                       Stearyl alcohol 25 17.7                                                     ______________________________________                                    

This ETPA was formed into a gel according to the procedure outlined inExample 1. The gel was hard but opaque, as summarized in Table 2.

EXAMPLE 9 ETPA From with very high C₂₄ Branched-chain Alcoholtermination

This example shows that a there is an upper limit to the alcoholconcentration that can be used in a forming an ETPA, and still obtain ahard gel. Above this limit, clear, extremely soft gels in tetradecaneare formed.

An ETPA was synthesized as in Example 1, using the reactants set forthin Table 10. The ETPA was very soft, having a melting point below roomtemperature. The viscosity of the ETPA at 130° C. was 20.5 cp.

                  TABLE 10                                                        ______________________________________                                        REACTANTS USED TO FORM A BRANCHED C.sub.24 ALCOHOL-                             TERMINATED POLYAMIDE                                                            Reactant         % Equivalents                                                                            Weight %                                      ______________________________________                                        Empol ™ 1008  100        51.5                                                Hexamethylene Diamine 30 3.1                                                  Iso Tetracosanol 70 45.4                                                    ______________________________________                                    

A gel was prepared from this ETPA as described in Example 1. The gel wasclear but very soft, as summarized in Table 2.

EXAMPLE 10 ETPA From co-diacid and C₁₈ Linear alcohol

This example shows that a co-diacid can be added to the ETPA formulationto increase the gel hardness while maintaining clarity.

An ETPA was synthesized as in Example 3, charging the co-diacid beforeheating. The reactants listed in Table 11 were used to form this ETPA.The product had a softening point of 133.5° C. and a viscosity at 190°C. of 26 cp.

                  TABLE 11                                                        ______________________________________                                        REACTANTS USED TO FORM A LINEAR C.sub.18 ALCOHOL-                               TERMINATED POLYAMIDE WITH 10% SEBACIC ACID                                      Reactant         % Equivalents                                                                            Weight %                                      ______________________________________                                        Empol ™ 1008  90         67.8                                                Sebacic Acid 10 2.7                                                           Ethylene Diamine 65 5.1                                                       Stearyl alcohol 35 24.4                                                     ______________________________________                                    

Using the procedure of Example 1, a gel was formed from this ETPA. Thegel was clear and hard, as summarized in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    THE PHYSICAL AND GEL PROPERTIES OF ETPAs MADE FROM                              VARIOUS ALCOHOL SIZES AND CONCENTRATIONS                                    Ex.                                                                              Alcohol  Alc. Conc.                                                                         Soft. Pt.                                                                         Viscosity                                                                             20 wt % ETPA in                                    No. Chain (% eq.) (° C.) (cP) tetradecane                            __________________________________________________________________________    7  4 (linear)                                                                             50   77.2                                                                              15 @ 190° C.                                                                   clear, hard gel                                    6 4 (linear) 35 86.3 35 @ 190° C. opaque, soft gel,                         syneresis                                                                5 10 (linear) 35 93.2 29 @ 190° C. opaque, hard gel                    1 14, 16 (linear) 50 68.5 44 @ 130° C. clear, soft gel                 3 18 (linear) 35 85.7 27 @ 190° C. clear, hard gel                     8 18 (linear) 25 90.4 47 @ 190° C. opaque, hard gel                    10 18 (+10% sebacic) 35 133.5 26 @ 190° C. clear, hard gel                                         2 22 (linear) 60 73.1 36.5 @ 130° C.                                  clear, soft gel                                    9 24 (branched) 70 ≈RT 20.5 @ 130° C. clear, very soft                                    gel                                                4 24 (branched) 40 85.2 20 @ 190° C. clear, hard gel                 __________________________________________________________________________

EXAMPLE 11 Effect of Alcohol Chain Length on Gel Clarity

This Example shows that the chain length of the alcohol used to preparean alcohol terminated polyamide, will have an affect on the clarity ofthe gel made from that polyamide. This Example further shows that theconcentration of gellant in a hydrocarbon medium will affect the clarityof the gel.

The alcohol terminated polyamides of Example Nos. 6 (C₄ linear alcohol),5 (C₁₀ linear alcohol) and 3 (C₁₈ linear alcohol) were dissolved in hottetradecane at concentrations ranging from 10 to 30 wt % based on thetotal weight of ETPA and tetradecane. Upon cooling, the resulting gelswere evaluated for clarity with the results as set forth in Table 12.

                  TABLE 12                                                        ______________________________________                                        GEL CLARITY AS A FUNCTION OF GELLANT CONCENTRATION                              AND THE CHAIN LENGTH OF THE ALCOHOL USED TO                                   PREPARE THE GELLANT                                                                                Wt % Gellant In Tetradecane + Gellant                    Example Alcohol Mixture                                                     Number  Chain Length                                                                             10      15    20    30                                     ______________________________________                                        6       C.sub.4    Opaque  Opaque                                                                              Opaque                                                                              Opaque                                   5 C.sub.10 Opaque Opaque Opaque Translucent                                   3 C.sub.18 Opaque Clear Clear Clear                                         ______________________________________                                    

The data of Table 12 shows that none of the ETPAs form clear gels at 10wt % solids. At 15 wt. % and 20 wt. % gellant using tetradecane, onlythe stearyl alcohol-terminated polyamide forms clear gels.

EXAMPLE 12 Effect Of Hydrocarbon On Gel Hardness And Clarity

When the ETPAs of Example 11 were used to form gels in deca in, the gelsshowed improved clarity however tended to be softer. The claritybehavior described in Example 11 is essentially reproduced whentetradecane is replaced with isooctane or with PD 23 (a hydrocarbonblend from Witco, Corp., Greenwich, Conn.). In isooctane, a gel tends tobe harder compared to when decalin is used, however softer than whentetradecane is used.

EXAMPLE 13 ETPA Composition Used For Gelling A Hydrocarbon Solvent

This example shows how an ETPA can be used to produce a clear, hard gelin PD 23 hydrocarbon, where PD 23 is a petroleum distillate made byWitco (Greenwich, Conn.) that has a viscosity of 2.6 cSt at 40° C. and aflash point of 230° F. PD-23 hydrocarbon is used in household productssuch as furniture polishes, household cleaners, liquid candles, and handcleaners.

A gel was prepared from the ETPA made according to Example 3. The gelwas made by heating 20% (by weight) of the ETPA in PD-23 until the ETPAhad dissolved. The solution was allowed to cool and a clear, hard gelwas formed.

EXAMPLE 14 ETPA Gel With KLEAROL Hydrocarbon

This example shows how the ETPA prepared as in Example 3 can be used togel a low viscosity, white mineral oil. The mineral oil used wasKlearol® (Witco Corp., Greenwich, Conn.) which has a viscosity of 7-10cSt at 40° C. and a flash point of 310° F. Klearol® mineral oil is usedin personal care products such as cleansing creams, hand cleansers,costume makeup, lipsticks, and hair care products. When gelled with theETPA at 20% solids, the gel was clear and hard.

EXAMPLE 15 ETPA Gel With KAYDOL Hydrocarbon

This example shows how the ETPA prepared as in Example 3 can be used togel a high viscosity, white mineral oil. The mineral oil used wasKaydol®, which has a viscosity of 64-70 cSt at 40° C., a flash point of430° F. and is available from Witco Corp. Kaydol® mineral oil is used inbath oil, suntan oil, moisturizing creams, and foundation makeup. Whengelled with the ETPA at 30% solids, the gel was clear and hard.

EXAMPLE 16 ETPA Gel With A Monofunctional Ester Solvent

This example shows how the ETPA prepared as in Example 3 can be used togel a mono-functional ester. The ester was a C₁₂₋₁₅ alkyl benzoatecalled Finsolv® TN, made by Fintex (Elmwood Park, N.J.). When gelledwith the ETPA at 10% solids, the gel was clear and hard.

EXAMPLE 17 ETPA Gel With A Monofunctional Ester Solvent

This example shows how the ETPA prepared as in Example 3 can be used togel a mono-functional ester. The ester was isopropyl isostearate(Unimate IPIS, made by Union Camp, Wayne, N.J.). When gelled with theETPA at 20% solids, the gel was clear and hard.

EXAMPLE 18 ETPA Gel With A Multifunctional Ester Solvent

This example shows that a multi-functional ester can be gelled with theETPA prepared as in Example 3. The ester was castor oil. When combinedwith the ETPA at 20% solids, a clear, hard gel was formed.

EXAMPLE 19 ETPA Gel With Terpene Hydrocarbon Solvent

This example shows that a terpene hydrocarbon solvent can be gelled withan ETPA. An ETPA was prepared using the procedure of Example 8. Theresultant ETPA was combined with limonene at 20% solids to yield aclear, firm gel.

EXAMPLE 20 Comparative Example

In this comparative example, an ETPA was made by first synthesizing apolyamide from Empol 1008 hydrogenated dimer (Henkel Corp. Ambler, Pa.)and EDA resulting in a polyamide with an amine number of 3 and asoftening point of 115° C. 100 g of this polyamide was heated undernitrogen with 66 g of Empol 1008 at 230° C. for 50 minutes. The mixturewas cooled to 110° C. and 30 g of ethanol and 2 ml of HCI were added.The mixture was heated under reflux conditions and the temperature wasallowed to reach 230° C. The acid number was checked periodically andethanol was added (at 110° C.) until the acid number was less than 30.At 230° C., vacuum was held on the mixture for 0.5 h and the ETPA waspoured. The resultant ETPA has an acid number of 25 and a softeningpoint of 80° C.

The ETPA was combined with tetradecane at 20% and heated until the ETPAdissolved. Upon cooling, an opaque, soft gel formed that showedsyneresis.

EXAMPLE 21 Comparative Example

This comparative example repeats Example 20, however the esterificationwas done at much lower temperatures. The polyamide described in Example20 (softening point=115° C.) was heated under reflux with Empol 1008 at230° C. in the same proportions as in Example 20 for 50 min. Thismixture was then cooled to 25° C. and ethanol and HCl were added in thesame proportions as in Example 20. The mixture was heated under refluxat 80-85° C. for eight hours and the excess ethanol was removed in anitrogen stream at 100° C. The resultant product had an acid number of17 and a softening point of 83° C. This material at 20% level was thenheated in tetradecane until dissolved. After the mixture cooled, anopaque, soft gel formed that showed syneresis.

EXAMPLE 22 Comparative Example

This comparative example shows that the ETPA made in Example 21 iscapable of thickening linseed oil, a component of alkyd paints. The ETPAmade in Example 21 at 10% level was heated in linseed oil untildissolved. Upon cooling, an opaque, thickened product was formed.

EXAMPLE 23

This example shows that the ETPA made according to the present methodthickens linseed oil. The ETPA made in Example 3 at 10% level was heatedin linseed oil until dissolved. Upon cooling, an opaque, thickenedproduct was formed.

EXAMPLE 24

This example shows that an ETPA can be used to gel an oil-based mixturewith an active ingredient. 10 g of the ETPA prepared as in Example 8 washeated in 15 g methyl salicylate, 4 g menthol (active ingredient), and21 g of KAYDOL (white mineral oil) until the ETPA was dissolved. Whenthe solution cooled, a clear, firm gel was formed.

EXAMPLE 25 Candle Preparation

This Example demonstrates that an ETPA resin can be used to make a clearcandle. The candle was prepared by combining 60 parts DRAKEOL 7 mineraloil (from Penreco, a division of Pennzoil Products Company, Kams City,Pa.) and 40 parts of the ETPA prepared in Example 8, and heating thecombination to about 110° C. until a clear, visually homogeneoussolution is obtained. The hot mixture is then poured into a shallow dishthat contains a wick. Upon cooling, a clear, freestanding candle isformed. The candle does not emit smoke when lit, and no discolorationwas observed after burning.

Throughout the present specification, where resins or reaction mixturesare described as including or comprising specific components ormaterials, it is contemplated by the inventors that the resins orreaction mixtures of the present invention also consist essentially of,or consist of, the recited components or materials. Accordingly,throughout the present disclosure any described composition (resin orreaction mixture) of the present invention can consist essentially of,or consist of, the recited components or materials.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

We claim:
 1. A method for preparing a resin composition comprisingester-terminated polyamide, the method comprising reacting x equivalentsof carboxylic acid from diacid or a reactive equivalent thereof, yequivalents of amine from diamine and z equivalents of hydroxyl frommonoalcohol or a reactive equivalent thereof, wherein at least about 50%of the carboxylic acid equivalents are from polymerized fatty acid,monoalcohol is substantially the only monofunctional reactant used toform the resin, the monoalcohol has at least four carbon atoms,0.9≦{x/(y+z)}≦1.1, and 0.1≦{z/(y+z)}≦0.7.
 2. The method of claim 1wherein a reaction mixture comprising diacid, diamine and monoalcoholare reacted to yield the resin.
 3. The method of claim 1 wherein areaction mixture consisting essentially of x equivalents of carboxylicacid from diacid, y equivalents of amine from diamine and z equivalentsof hydroxyl from monoalcohol is heated to yield the resin.
 4. The methodof claim 1 wherein all equivalents of carboxylic acid come frompolymerized fatty acid.
 5. The method of claim 1 wherein between 1% and50% of the carboxylic acid equivalents come from a diacid of the formulaHOOC--R² --COOH wherein R² is a C₄₋₁₉ hydrocarbon group.
 6. The methodof claim 1 wherein the diamine has the formula H₂ N--R³ --NH₂ and R³ isa C₂₋₃₆ hydrocarbon group.
 7. The method of claim 1 wherein at least 50%of the amine equivalents are contributed by a diamine of the formula H₂N--R³ --NH₂ wherein R³ is a C₂₋₃₆ hydrocarbon group, and at least 1% ofthe amine equivalents are contributed by one or more diamines selectedfrom ##STR8## and H₂ N--R³ --NH₂, wherein R³ is selected frompolyalkylene oxide, polyalkylene amine, or ##STR9## wherein R_(c) is aC₁₋₃ alkyl group.
 8. The method of claim 1 wherein the monoalcohol hasthe formula R¹ --OH and R¹ is a C₁₂₋₂₂ hydrocarbon group.
 9. The methodof claim 1 wherein x/(y+z) is substantially equal to
 1. 10. The methodof claim 1 wherein 0.2≦{z/(y+z)}≦0.5.
 11. The composition prepared bythe method of claim
 1. 12. The composition of claim 11 furthercomprising a low polarity liquid.
 13. The composition of claim 12 whichis transparent or translucent.
 14. The composition of claim 12 which isa self-supporting gel.
 15. The composition of claim 12 which does notdisplay syneresis.
 16. The composition of claim 12 having at least about5 weight percent and less than about 50 weight percent of the resincomposition, based on the total weight of low polarity liquid and theresin composition.
 17. The composition of claim 12 wherein the lowpolarity liquid comprises a hydrocarbon.
 18. The composition of claim 17wherein the hydrocarbon is an oil.
 19. A method for preparing atransparent or translucent gel, comprising combining a low polarityliquid with a resin composition, the resin composition comprisingester-terminated polyamide of formula (1): ##STR10## wherein ndesignates a number of repeating units such that ester groups are from10% to 50% of the total of the ester and amide groups;R¹ at eachoccurrence is independently selected from an alkyl or alkenyl groupcontaining at least 4 carbon atoms; R² at each occurrence isindependently selected from a C₄₋₄₂ hydrocarbon group with the provisothat at least 50% of the R² groups have 30-42 carbon atoms; R³ at eachoccurrence is independently selected from an organic group containing atleast two carbon atoms in addition to hydrogen atoms, and optionallycontaining one or more oxygen and nitrogen atoms; and R³ at eachoccurrence is independently selected from hydrogen, C₁₋₁₀ alkyl and adirect bond to R³ or another R^(3a) such that the N atom to which R³ andR^(3a) are both bonded is part of a heterocyclic structure defined inpart by R^(3a) --N--R³, such that at least 50% of the R^(3a) groups arehydrogen.
 20. A method for preparing a transparent or translucent gel,comprising combining a low polarity liquid with a resin according toclaim
 11. 21. A cosmetic comprising a resin composition comprisingester-terminated polyamide of formula (1): ##STR11## wherein ndesignates a number of repeating units such that ester groups are from10% to 50% of the total of the ester and amide groups;R¹ at eachoccurrence is independently selected from an alkyl or alkenyl groupcontaining at least 4 carbon atoms; R² at each occurrence isindependently selected from a C₄₋₄₂ hydrocarbon group with the provisothat at least 50% of the R² groups have 30-42 carbon atoms; R³ at eachoccurrence is independently selected from an organic group containing atleast two carbon atoms in addition to hydrogen atoms, and optionallycontaining one or more oxygen and nitrogen atoms; and R^(3a) at eachoccurrence is independently selected from hydrogen, C₁₋₁₀ alkyl and adirect bond to R³ or another R^(3a) such that the N atom to which R³ andR^(3a) are both bonded is part of a heterocyclic structure defined inpart by R^(3a) --N--R³, such that at least 50% of the R^(3a) groups arehydrogen.
 22. A cosmetic comprising the composition of claim
 11. 23. Apersonal care product comprising a resin composition comprisingester-terminated polyamide of formula (1): ##STR12## wherein ndesignates a number of repeating units such that ester groups are from10% to 50% of the total of the ester and amide groups;R¹ at eachoccurrence is independently selected from an alkyl or alkenyl groupcontaining at least 4 carbon atoms; R² at each occurrence isindependently selected from a C₄₋₄₂ hydrocarbon group with the provisothat at least 50% of the R² groups have 30-42 carbon atoms; R³ at eachoccurrence is independently selected from an organic group containing atleast two carbon atoms in addition to hydrogen atoms, and optionallycontaining one or more oxygen and nitrogen atoms; and R^(3a) at eachoccurrence is independently selected from hydrogen, C₁₋₁₀ alkyl and adirect bond to R³ or another R^(3a) such that the N atom to which R³ andR^(3a) are both bonded is part of a heterocyclic structure defined inpart by R^(3a) --N--R³, such that at least 50% of the R^(3a) groups arehydrogen.
 24. A personal care product comprising the composition ofclaim 11.